Cooling systems, controllers and methods

ABSTRACT

Aspects of liquid operational systems are described. According to one aspect, a system to automatically fill a liquid operational component is described. According to another aspect, a self-diagnostic system is described. According to yet another aspect, a flow conditioning arrangement is described. A control system for a heat-transfer system includes a plurality of sensors. Each sensor is configured to observe an operational parameter indicative of a thermodynamic quantity and to emit a signal containing information corresponding to the observed operational parameter. Control logic includes a processing unit and instructions stored on a memory that, when executed by the processing unit, cause the control logic to determine a first thermodynamic quantity associated with each sensor from information contained in a signal from the respective sensor; determine a second thermodynamic quantity associated with each sensor from information contained in a signal received from at least one other sensor in the plurality of sensors; compare the first thermodynamic quantity with the second thermodynamic quantity; and responsive to the comparison of the first thermodynamic quantity with the second thermodynamic quantity, output a control signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and benefit of co-pendingprovisional U.S. Patent Application No. 62/571,420 filed on Oct. 12,2017.

BACKGROUND

This application pertains to concepts disclosed in co-pending U.S.patent application Ser. No. 15/354,982, which claims benefit of andpriority from U.S. Patent Application No. 62/256,519, filed Nov. 17,2015, and benefit of and priority from U.S. patent application Ser. No.14/777,510, filed Sep. 15, 2015, which is a U.S. National PhaseApplication of International Patent Application No. PCT/IB2014/059768,filed Mar. 14, 2014, which claims benefit of and priority to U.S. PatentApplication No. 61/793,479, filed Mar. 15, 2013, U.S. Patent ApplicationNo. 61/805,418, filed Mar. 26, 2013, U.S. Patent Application No.61/856,566, filed Jul. 19, 2013, and U.S. Patent Application No.61/880,081, filed Sep. 19, 2013, each of which patent applications ishereby incorporated by reference in its entirety as if fully set forthherein, for all purposes.

Other pertinent disclosures include U.S. Patent Application No.61/522,247, filed Aug. 11, 2011, U.S. Patent Application No. 61/622,982,filed Apr. 11, 2012, U.S. Patent Application No. 61/794,698, filed Mar.15, 2013, U.S. patent application Ser. No. 13/559,340, filed Jul. 26,2012, now U.S. Pat. No. 9,496,200, U.S. Patent Application No.61/908,043, filed Nov. 23, 2013, and U.S. patent application Ser. No.14/550,952, filed Nov. 22, 2014, each of which patent applications ishereby incorporated by reference in its entirety as if fully set forthherein, for all purposes.

The innovations and related subject matter disclosed herein(collectively referred to as the “disclosure”) pertain to control offluid-flows in heat-transfer systems, and more particularly, but notexclusively, to systems, controllers and methods for governing flows andcontrolling pumps, e.g., in correspondence with one or more observeddifferential-pressures within a heat-transfer system.

For example, a typical server rack of the type used in a data center canaccommodate 42 individual servers, each server corresponding to acooling node within a heat-transfer system. Naturally, some server rackscan accommodate more or fewer individual servers. As well, some serverracks might not be fully populated. Some coolant-distributers use one ormore rack-level (e.g., “centralized”) pumps to distribute coolant amonga plurality of connected cooling nodes, and it would be desirable for agiven coolant-distributer embodiment to be suitable for use across avariety of server-rack configurations, such as for use with afully-populated 42 U rack housing 42 individual servers, as well as alightly populated 10 U rack housing, e.g., 5 individual servers, and acustom 60 U rack housing 60 (or more) individual servers.

Conventionally, coolant-distributers have been designed to operate undera maximum expected load, e.g., without being adjustable to operate atlesser loads. For example, a conventional coolant-distributer for atypical 42 U rack typically has one or more pumps arranged and selectedto distribute coolant among 42 individual cooling nodes (e.g., one nodefor each of 42 individual servers housed in the 42 U rack). In thatexample, the pumps can be selected to operate efficiently and to deliveran optimal pressure-head and optimal flow-rates to the various nodesthroughout the cooling system when such a conventionalcoolant-distributer is used in conjunction with a fully-populated serverrack. Nonetheless, such pumps may operate less efficiently and/or maydeliver less-than-optimal (e.g., a too-high or a too-low) pressure-headsand (e.g., a too-high or a too-low) flow-rates when more or fewercooling nodes are connected to the coolant-distributer as compared to anumber of cooling nodes assumed to be connected when choosing an“optimal” design configuration.

For example, a conventional coolant-distributer may be designed todeliver coolant to 42 cooling nodes at a pressure of about 12 psi. If,say, 35 cooling nodes are disconnected from the conventional coolantdistributer, the pumps may deliver coolant at a substantially higherpressure head and may not operate as efficiently and/or may consumehigher power as compared to when 42 cooling nodes are connected.

SUMMARY

Innovations and related subject matter disclosed herein overcome manyproblems in the prior art and address one or more of the aforementioned,or other, needs. This disclosure pertains generally to control offluid-flows in heat-transfer systems, for example, systems, controllersand methods for governing flows and controlling pumps in correspondencewith one or more observed differential-pressures within a heat-transfersystem. Such systems, controllers and methods can provide desired flowrates among each in a plurality of connected cooling nodes, despite thatthe number in the plurality can vary between about 1 node and about 60nodes, for example. Nonetheless, disclosed concepts can be applied to alarger range of cooling nodes and/or larger or smaller numbers ofcooling nodes.

Embodiments of cooling systems, controllers and methods can providedesired flow-rates and pressure-heads under a variety of cooling-systemconfigurations. For example, certain embodiments of cooling systems,controllers and methods provide coolant to each in a selected pluralityof cooling nodes (each corresponding to an individual server) within aselected range of flow rates and a selected range of pressures, despitethat the selected plurality of cooling nodes can range in number, forexample, between about 1 node and about 60 nodes, such as between about5 nodes and about 50 nodes, with between about 8 nodes and about 42nodes being but one particular range of nodes.

According to one aspect, a system includes an enclosure having an inletto the enclosure and a wall at least partially defining a boundary ofthe enclosure. The enclosure is configured to receive a liquid from theinlet and to contain the received liquid. An aperture is in the wall. Aconduit is coupled with the aperture, wherein the conduit comprises asegment extending into the enclosure from the aperture. A baffle definesa corresponding plurality of apertures and is positioned between theinlet and the segment of the conduit. The baffle is oriented such thatliquid received from the inlet passes through the plurality of aperturesin the baffle before entering the segment of conduit.

The segment of conduit extending into the enclosure can define anarcuate segment such that an end of the segment of conduit is positionedlower, relative to gravity, than a centroid of the aperture in the wall.The segment of the conduit extending into the enclosure can define anend positioned distally from the aperture in the wall. The end candefine a second aperture and the second aperture can be orientedtransversely relative to the aperture in the wall.

The segment of the conduit extending into the enclosure can define anend positioned distally from the aperture in the wall. The end candefine a second aperture and the second aperture can be orientedtransversely relative to the baffle.

The baffle can be a first baffle and the corresponding plurality ofapertures can be a first plurality of apertures. The system can alsohave a second baffle defining a second plurality of apertures.

Each of the first plurality of apertures and the second plurality ofapertures can have a corresponding hydraulic diameter. Each hydraulicdiameter can be characteristic of the respective plurality of apertures.The hydraulic diameter characteristic of the first plurality ofapertures can differ from the hydraulic diameter characteristic of thesecond plurality of apertures. A hydraulic diameter characteristic ofthe first plurality of apertures can be substantially equal of ahydraulic diameter characteristic of the second plurality of apertures.

The baffles can be arranged in order of decreasing hydraulic diameteralong a direction extending from the inlet to the conduit segment.

The plurality of apertures of the first baffle can be offset from theplurality of apertures of the second baffle.

According to an aspect, a system can include a reservoir defining aninlet and an outlet. The reservoir can be configured to hold a liquidreceived from the inlet. The system can include a pump and a fluidconditioning unit. The pump can be fluidically coupled to the reservoirand configured to pump the liquid from the reservoir to the fluidconditioning unit. A sensor can be configured to observe an operationalparameter associated with the fluid conditioning unit. The system caninclude control logic. The control logic can be configured tocommunicate a control signal to the pump, receive a signal from thesensor; and iteratively activate and deactivate the pump via the controlsignal until the signal received from the sensor comprises an indicationthat the fluid conditioning unit is filled with a liquid to a specifiedamount.

Such a system can also include a fill tank fluidically coupled to thereservoir. The system can include a second pump configured to pumpliquid from the fill tank to the reservoir. The control logic can beconfigured to communicate a second control signal to the second pump toactivate and deactivate the second pump.

The sensor can be a temperature sensor, a pressure sensor, a liquiddetection sensor, a flow sensor, or a fluid level sensor, for example.

The system can include plurality of pumps fluidically coupled to thereservoir. Each of the plurality of pumps can be configured to pump theliquid from the reservoir to a closed-loop liquid system.

The control logic can be configured to iteratively activate anddeactivate each of the plurality of pumps.

The control logic can be configured to iteratively activate anddeactivate each of the plurality of pumps sequentially. The controllogic can be configured to iteratively activate and deactivate each ofthe plurality of pumps concurrently or jointly.

According to an aspect, control systems are described. A control systemcan be for a heat-transfer system. Such a control system can include aplurality of sensors. Each sensor can be configured to observe anoperational parameter indicative of a thermodynamic quantity and to emita signal containing information corresponding to the observedoperational parameter. Control logic can include a processing unit andinstructions stored on a memory that, when executed by the processingunit, cause the control logic to determine a first thermodynamicquantity associated with each sensor from information contained in asignal from the respective sensor. The instructions, when executed bythe processor, can further cause the control logic to determine a secondthermodynamic quantity associated with each sensor from informationcontained in a signal received from at least one other sensor in theplurality of sensors. The instructions, when executed by the processor,can further cause the control logic to compare the first thermodynamicquantity with the second thermodynamic quantity; and responsive to thecomparison of the first thermodynamic quantity with the secondthermodynamic quantity, output a control signal.

The instructions that cause the control logic to output a control signalresponsive to the comparison of the first thermodynamic quantity withthe second thermodynamic quantity can include instructions to output thecontrol signal responsive to a difference between the firstthermodynamic quantity and the second thermodynamic quantity exceeding athreshold difference, or instructions to output the control signalresponsive to a difference between the first thermodynamic quantity andthe second thermodynamic quantity falling below a threshold difference.

The plurality of sensors can include a temperature sensor. Theinstructions that cause the control logic to determine a secondthermodynamic quantity can include instructions that cause the controllogic to predict a temperature corresponding to the temperature sensorfrom information contained in a signal received from at least one othersensor in the plurality of sensors.

The plurality of sensors can include a pressure sensor. The instructionsthat cause the control logic to determine a second thermodynamicquantity can include instructions that cause the control logic topredict a pressure corresponding to the pressure sensor from informationcontained in a signal received from at least one other sensor in theplurality of sensors.

Other innovative aspects of this disclosure will become readily apparentto those having ordinary skill in the art from a careful review of thefollowing detailed description (and accompanying drawings), whereinvarious embodiments of disclosed innovations are shown and described byway of illustration. As will be realized, other and differentembodiments of systems, controllers and methods incorporating one ormore of the disclosed innovations are possible and several discloseddetails are capable of being modified in various respects, each withoutdeparting from the spirit and scope of the principles disclosed herein.For example, the detailed description set forth below in connection withthe appended drawings is intended to describe various embodiments of thedisclosed innovations and is not intended to represent the onlycontemplated embodiments of the innovations disclosed herein. Instead,the detailed description includes specific details for the purpose ofproviding a comprehensive understanding of the principles disclosedherein. Accordingly the drawings and detailed description are to beregarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Unless specified otherwise, the accompanying drawings illustrate aspectsof the innovative subject matter described herein. Referring to thedrawings, wherein like reference numerals indicate similar partsthroughout the several views, several examples of systems incorporatingaspects of the presently disclosed principles are illustrated by way ofexample, and not by way of limitation.

FIG. 1A illustrates a modular heat-transfer system configured to cool aplurality of independently operable, rack-mounted servers.

FIG. 1B shows an isometric view of a portion of the modularheat-transfer system shown in FIG. 1, together with features of aheat-transfer element.

FIG. 1C shows a block diagram of a liquid-cooled heat exchange systemconfigured to cool servers in a rack-mountable server system.

FIG. 2 shows an isometric view of a reservoir tank and a pump.

FIG. 3 shows a side-elevation view of a reservoir tank and a pump.

FIG. 4 shows an isometric view of another reservoir tank having abaffle.

FIG. 5 shows aspects of a baffle.

FIG. 6 shows a reservoir tank having two baffles, with each orientedvertically.

FIG. 7 shows a reservoir tank having a horizontally oriented baffle.

FIG. 8 shows a top-down view of a reservoir tank having three verticallyoriented baffles. The baffles are substantially orthogonal to selectedside walls of the reservoir tank.

FIG. 9 shows a top-down view of another reservoir tank having threevertically oriented baffles oriented at obtuse-acute angles relative toselected side walls.

FIG. 10 shows a top-down view of a reservoir tank having a curvedbaffle.

FIG. 11 shows a top-down view of a reservoir tank having a singularcircular or ovoid cross-section, and where two baffles are used.

FIG. 12 shows a top-down view of a cylindrical reservoir tank.

FIGS. 13A-C shows examples of different shapes of baffle apertures.

FIG. 14 shows an example of a series of baffles having offset apertures.

FIG. 15 shows a block diagram of a closed-loop liquid system having afluid conditioning unit.

FIG. 16 shows a block diagram of a closed-loop liquid system that is aliquid-cooled heat exchange system having a fluid conditioning unit.

FIG. 17 shows a logic flow diagram that may be executed by control logicin a closed-loop liquid system having a pump, during an initial fillingoperation.

FIG. 18 illustrates a generalized example of a suitable computingenvironment for implementing one or more technologies described herein.

DETAILED DESCRIPTION

The following describes various principles related to systems,controllers and methods by way of reference to specific examples ofsystems, controllers and methods, including specific arrangements ofpumps, heat exchangers, conduits, sensors, and actuators, as well asspecific examples of data structures, data types, computations, statevariables, equations-of-state, performance targets, performancecharacteristics, performance variables and system, data, andcomputational architectures embodying innovative concepts. Moreparticularly, but not exclusively, such innovative principles aredescribed in relation to selected examples of systems, controllers andmethods for purposes of succinctness and clarity. Nonetheless, one ormore of the disclosed principles can be incorporated in various otherembodiments of systems, controllers and methods to achieve any of avariety of desired outcomes, characteristics, and/or performancecriteria. Systems, controllers and methods described in relation toparticular configurations, applications, uses, or acts are merelyexamples of systems, controllers and methods incorporating one or moreof the innovative principles disclosed herein and are used to illustrateone or more innovative aspects of the disclosed principles.

Thus, systems, controllers and methods having attributes that aredifferent from those specific examples discussed herein can embody oneor more of the innovative principles, and can be used in applicationsnot described herein in detail, for example, to detect a failed sensor,to confirm a measure of health of a sensor, and/or to detect a leak of afluid (e.g., a liquid, a gas, or a saturated mixture thereof) from, orto observe a local speed of a flow of such a fluid through, aheat-transfer system having any of a variety of flow configurations,such as a contained flow within a fluid conduit or a free-stream flow(e.g., a region of a fluid flow sufficiently spaced from a fluidboundary as not to be influenced by the boundary). Accordingly,embodiments of systems, controllers and methods not described herein indetail also fall within the scope of this disclosure, as will beappreciated by those of ordinary skill in the art following a review ofthis disclosure.

Overview

FIG. 1A shows an array 150 of independently operable servers 112 a, 112b . . . 112 n mounted in a rack, or chassis, together with aspects of aheat-transfer system for cooling the servers. In FIG. 1A, each server112 has one or more corresponding heat sources.

A heat-transfer system can collect heat from each heat source and carrythe heat to a suitable heat sink, e.g., a facility liquid and/or air ina conditioned room containing the rack of servers. Thus, such aheat-transfer system can include several different components arrangedto dissipate heat from any of a variety of heat sources to one or moreheat sinks.

For example, in FIG. 1A, a fluid-conditioning unit (also sometimesreferred to as a coolant heat-exchange unit) 10 is shown. The fluidconditioning unit 10 can receive a warm coolant carrying heat from theservers 112 a-n and facilitate transfer of that heat to another medium.The fluid conditioning unit 10 can return the coolant to the servers tocollect further heat from the servers.

FIG. 1B illustrates aspects of a representative heat-transfer element110 within the heat-transfer system shown in FIG. 1A. The heat-transferelement 110 corresponds to one of the servers 112 a-n. The heat-transferelement 110 can be thermally coupled to a corresponding one or morecomponents that dissipate(s) heat during operation of the respectiveserver. In FIG. 1B, the heat-transfer element 110 has two constituentcomponent heat-exchange modules 120 a, 120 b, each of which can bethermally coupled with a corresponding heat-dissipation element (e.g., aprocessing unit) within the server 112. As coolant passes through eachrespective heat-transfer module 120 a, 120 b, the coolant can absorbheat dissipated by the heat-dissipation element. The warmed coolant canthen be carried to the fluid-conditioning unit 10, where the heat istransferred to another medium (e.g., facility water). Such anarrangement for cooling rack mounted servers is described in furtherdetail in U.S. Pat. No. 9,496,200. Representative heat-exchange modulesare described in further detail in U.S. Pat. Nos. 8,746,330 and9,453,691. The heat-exchange modules can be passive, as in the '330Patent, or they can be active, e.g., include a pump, as in the '691Patent.

FIG. 1C schematically illustrates a cooling system suitable for coolingan array of rack mounted servers 1650, similar to the rack of servers150 in FIGS. 1A and 1B. In FIG. 1C, the fluid conditioning unit 1600 isarranged similarly to the fluid conditioning unit 10 in FIG. 1A. Theconditioning unit 1600 includes a reservoir 1610 and a plurality ofdistribution pumps 1620-1 to 1620-n. Coolant collected from the rack ofservers 1650 (e.g., by a collection manifold 1654) can flow into thereservoir 1610 and can be pumped by the distribution pump(s) 1620-1 to1620-n to an environmental coupler (e.g., a heat exchanger 1630). In theenvironmental coupler, heat carried by the coolant can be transferred toanother medium (e.g., facility water), cooling the coolant flowingthrough the environmental coupler. The cooled coolant can then pass backto the rack of servers 1650 (e.g., distributed among the plurality ofservers in the rack by the distribution manifold 1652).

In FIG. 1C, the fluid conditioning unit 1600 includes control logic1640. The control logic can receive information from one or more sensorsoperatively coupled with any of the components, devices, structures,mechanisms, racks, servers, heat-transfer systems, processing units,computing environments, actuators, etc., described herein. The controllogic can process the received information and, responsive to an outputof such processing, can emit one or more signals, commands, etc. Acomponent, device, structure, mechanism, rack, server, heat-transfersystem, processing unit, computing environment, actuator, etc.,described herein can receive an emitted signal or command. Suchcomponent, device, structure, mechanism, rack, server, heat-transfersystem, processing unit, computing environment, actuator, etc.,described herein can respond to a received signal or command emitted bythe control logic. Control logic can be implemented in a general purposecomputing environment, in an application specific integrated circuit, orin a combination of hardware and software (e.g., firmware).

As an example, a coolant distributer (sometimes also referred to as afluid conditioning unit) can have a variety of temperature, flow-rate,and/or pressure sensors arranged to observe temperature, flow-rate andpressure (e.g., static and/or stagnation) at one or more selectedlocations within a fluid circuit (open or closed). A controller canadjust operation of one or more coolant (e.g., a pump, a valve) and/orheat-transfer components (e.g., a logic or other component of acomputing environment) to achieve desired flow and/or coolingcharacteristics.

As but one example, if a static pressure difference across an inlet toand an outlet from a selected fluid circuit (or branch thereof) exceedsa selected upper threshold pressure, one or more pumps can be throttled,as by slowing an impeller speed, thereby reducing the static pressuredifference across the inlet and the outlet. Alternatively, if the staticpressure difference across the inlet and the outlet falls below aselected lower threshold pressure difference, the one or more pumps canbe operated at a higher impeller speed and/or one or more additionalpumps can be “brought online” to supplement or augment availablepressure head and flow delivery.

As another example, measurement of observable state-variables (e.g.,temperature, static pressure, mass, density) combined with knownmeasures of selected properties (e.g., specific heat, heat capacity,compressibility, gas constant, equation-of-state) of a given fluidand/or observable system performance characteristics (e.g., powerdissipation from a heat source), health and robustness of system sensorscan be assessed, as by control logic, and communicated to a system useror manager. For example, some disclosed systems, controllers and methodscan compute values of state variables at one or more selected locationswithin a selected fluid circuit (or branch thereof) and compare thecomputed value to an observed value detected from a given sensor.

If an absolute value of a difference between the computed value and theobserved value exceeds a selected threshold difference, an innovativecontrol logic, system, controller, or method implemented in controllogic, can determine a fault has occurred and can take a remedialaction, as by setting a flag, sending an e-mail, and/or initiating analarm to alert a user of the determined fault. Such a fault can indicatea failed or failing sensor, a leak, an over temperature condition, afailed pump, an under-speed pump, an over-speed pump, a failed orfailing controller (e.g., a pump controller).

Disclosed systems, controllers, control logic and methods also providefor automatic control of external fill systems. For example, a disclosedcoolant distributer can have a relay or other control output to cause anexternal pump (e.g., a pump associated with an external fill kit) toactuate in correspondence with a pump associated with the coolantdistributer. The relay or other control output can be actuatedresponsive to an observed and/or computed state of a coolant circuit (orbranch thereof). For example, a bleed-valve can be opened to permit acompressible gas escape from a conduit as the conduit fills with acoolant fluid (e.g., a substantially incompressible liquid). A fluidsensor or a leak detector can determine the conduit is full, as when aselected measure of the fluid is detected within or without the conduit.Responsive to such detection, the relay or other control output cancause the external pump to slow or cease operation, to speed up orincrease operation, can open or close a selected valve, and/or cause aninternal pump to slow, cease operation, speed up, or increase operationto achieve a desired outcome.

In yet another example, a pressure-relief or check-valve can open topermit a fluid to by-pass a selected fluid circuit or branch thereofresponsive to a selected measure of a fluid's state exceeding or fallingbelow a selected threshold. For example, the valve can open to allow afluid to by-pass a closed fluid conduit, as to prevent a pump from “deadheading” (e.g., operating without a flow of fluid through the pump), assuch “dead heading” can cause a pump to overheat and, eventually, tofail or otherwise be damaged.

Reservoir with Reduced Liquid Entrainment and Cavitation

In closed-loop liquid systems, such as, for example, a liquid-based heattransfer system or other hydraulic system, liquid may be pumped from areservoir, circulated to one or more other system components, andreturned to the reservoir. The reservoir may be positioned in someselected region of the system. The reservoir may have some amount of airor other gas in it in order to accommodate changes in the liquid'svolume in the tank, e.g., due to thermal expansions and contractions,despite that many liquids generally are considered and modeled to beincompressible. And, under sufficient pressures or temperatures, theliquid may change state (e.g., vaporize as through cavitation orseparation from a surface) to form a saturated mixture (at leastlocally), reducing the mass of liquid while increasing a mass of gas inthe closed system. It may, however, be undesirable to introduce a gasphase into other regions of the closed-loop system. For example, gasbubbles may damage pumps, or cause other harmful effects such as, butnot limited to, overheating (e.g., as by blocking a flow of liquidthrough a passage in a heat exchanger).

FIG. 2 shows an isometric view of a reservoir enclosure (sometimes alsoreferred to herein as a “tank”). The illustrated reservoir tank is asealed tank 100 where the liquid enters from an inlet 102 positioned ator near a top wall 104 of the reservoir.

An outlet aperture 106, located adjacent a floor or other bottom wall108 of the tank, e.g., on a side wall 110, connects to a liquid conduit112 that may also connect to a pump 114. The line 101 indicates a levelof a free surface of the liquid 105 in the tank. Gas is present in thevolume 103 above the line 101. The gas may be air, or a relatively inertgas such as, for example, nitrogen, or a mixture of saturatedvapor-phase of the liquid and air (or, e.g., nitrogen). When the liquid105 exits the tank through the outlet 106, either due to a pump or dueto gravity, the flow of the liquid through the outlet may begin torotate, causing a vortex in a region of the fluid positioned adjacentthe outlet, similar to a vortex that forms in a draining bathtub orsink. The vortex may entrain gas in the tank into the liquid and/or maycause cavitation to occur in the swirling flow. Under such conditions,gas may be entrained into the flow through the outlet 106 and introducethe gas into other regions of the closed loop system. As noted,entrained gas bubbles can deteriorate performance and even cause systemdamage.

Another potential source of damage to closed-loop liquid systems mayinclude cavitation. Cavitation refers to the formation and collapse ofvapor bubbles in a liquid, which can occur when a local static pressurein the liquid drops below the vapor pressure of the liquid. Cavitationcan occur, for example, when a liquid passes through a flowconstriction, as from a relatively large flow cross-section (e.g.,within the enclosure 100) through a smaller cross-sectional area (e.g.,through the aperture 106). For example, as a liquid-phase fluid passesfrom a tank to a tube, particularly by passing through a sharp-edgedorifice, streamlines of the flow may constrict to a smaller diameterthan a diameter (e.g., a hydraulic diameter) of the orifice, causing theflow to separate from the walls of the tube. In such a flow, a speed ofthe flow increases as the flow constricts, causing regions of lowerpressure, e.g., usually at the edges of the transition area, where theliquid flow can separate from a boundary wall and locally cavitate. Oncea cavitation (vapor) bubble moves back into a region of higher pressure,it collapses. The collapsing bubble releases a large amount of energy ina concentrated region and can erode surfaces of nearby structure (e.g.,walls). Additionally, the vapor bubbles are substantially less densethan the liquid phase and therefore carry less mass, effectivelyreducing a flow rate of liquid through the cavitation region.

In some cases, a swirling flow may cavitate. For example, in a swirlingflow such as a whirlpool, a local pressure within a vortex may drop to apressure at or below the vapor pressure of the liquid, inducingcavitation in those low-pressure regions.

Accordingly, various aspects of a reservoir of a closed-loop liquidsystem are described to inhibit or to altogether avoid entraining gasinto the liquid conduits, and to inhibit or altogether preventcavitation and its accompanying effects. In an embodiment, the shape andpositioning of the outlet from the reservoir enclosure may reduce alikelihood of either or both entrainment and the effects of cavitation.For example, a “snorkel” may be added to draw fluid into a conduit froman interior region of the tank, as opposed to drawing fluid into theconduit from a sidewall as shown in FIG. 2. Such snorkels are describedmore fully below.

Additionally, or alternatively, baffles may be added into the reservoirto prevent or inhibit gas entrainment or cavitation, as by inhibitinglarge-scale swirling flows from forming, disrupting formation of largevortices, straightening flows, etc. Such baffles are described morefully below.

The illustrated tank has a generally hollow, prismatic structure, e.g.,as a hollow rectangular prism. Of course, hollow enclosures of othershapes are possible and can incorporate aspects described in relation toFIG. 2 and other embodiments of tanks described herein.

FIG. 3 shows a side view of a reservoir tank 200. As with the tank 100in FIG. 1, a liquid may enter the tank 200 through an inlet 202 in thetop 204 of the tank. The inlet may be positioned, alternatively, in asidewall of the tank. The liquid conduit 212 is coupled to, and may passthrough, the outlet aperture 206 in the side wall 210 a. The outletaperture 206 may be, alternatively, positioned in the floor, at an edge,or in a corner of the tank. The tank 200 may be sealed, such thatsubstantially no gas or liquid can enter or leave the tank other thanthrough the inlet 202 and the outlet aperture 206 through the wall 210a.

The liquid conduit 212 can extend from a first end to an opposed secondend. The first end can be coupled with a pump such that an aperture 216at the first end of the liquid conduit 212 is coupled directly orindirectly to an inlet to a pump 214. The liquid conduit 212 can extendthrough a side wall 210 a such that the opposed second end of the liquidconduit 212 is positioned in the enclosure 200. An aperture 218 at theopposed second end can draw liquid from the enclosure into thepassageway of the conduit. In another embodiment, the second end of theconduit 212 couples with the wall 210 a, e.g., a flange on the wall. Asecond segment of conduit (not shown) can be coupled to the wall on aninterior surface of the enclosure, and an opposed distal end of thesecond segment can be positioned as illustrated in FIG. 3. In general,the liquid conduit(s) may be coupled to the outlet aperture from theenclosure with a flange, a pipe nipple, welding, or any other couplingthat allows the tank liquid to convey from the tank to the pump withoutleaking at the outlet aperture.

Another aperture, e.g., an aperture 218 at an opposite end of theconduit, may be positioned inside of the tank 200. And, instead ofextending straight into the tank, the liquid conduit 212 may curve orbend such that the aperture 218 is downwardly facing and open toward thebottom 208 of the tank.

Liquid flowing through the aperture 218, e.g., being urged by a pressuredifferential between the free surface 201 and an inlet to the pump, intothe conduit 212 will flow upward initially within the conduit, whileliquid entering the tank 200 from the inlet 202 and flowing from thefree-surface 201 to the inlet will flow downward, as shown by thearrows. Such a change in direction of the flow through the tank candisrupt and/or delay the onset of a swirling flow or a vortex that mayotherwise cavitate or entrain gas from above the free surface 201.

In FIG. 3, the aperture 218 is positioned at an elevation h₁ above thebottom of the tank. The conduit 212 is positioned above the bottom ofthe tank by an elevation h₂, which is greater than h₁. Stated anotherway, the outlet aperture 206 through the reservoir wall 210 a ispositioned above (at a higher elevation than) the aperture 218 of theconduit relative to the floor (as defined by gravity) of the reservoirtank. The conduit 212 may be positioned through the outlet aperture 206such that the conduit 212 is oriented perpendicularly or otherwisetransversely relative to the side wall 210 a. For example, the conduit212 may be angled through the outlet aperture 206 such that the conduit212 slopes up or down with respect to the tank.

The aperture 218 to the conduit 212 may have a planar orientation thatis parallel to the bottom 208. Alternatively, the planar orientation ofthe aperture 218 may be angled with respect to the bottom, e.g., notparallel to the bottom. Although a planar aperture is described forsuccinctness and clarity, the aperture may be non-planar. As well, theaperture may be one of several or many apertures opening to thepassageway 216 into the conduit. Further, additional curves or bends inthe conduit 212 may be used to orient the aperture 218 relative to(e.g., to be parallel with or transverse to one of the side walls).Orienting the aperture 218 to face, and be parallel to, an opposite sidewall 210 b, however, may be less effective than a generally downwardlyfacing aperture (as in FIG. 3) at inhibiting swirling flows or gasentrainment, particularly if the aperture 218 is positioned relativelyfar from the inlet or a side wall (e.g., more than a selected number of(e.g., 1, 2, 5, 10) hydraulic diameters of the conduit), as such anorientation would be similar to having the aperture 218 at the tankoutlet aperture 206. Orienting the aperture 218 to face, and be parallelto, the opposite side wall 210 b, at a distance less than acharacteristic dimension of a swirling flow, e.g., relatively close toor even behind the inlet relative to the outlet, may tend to disrupt theformation of a swirling flow and thus inhibit entrainment. Such acharacteristic dimension may be a selected number of (e.g., 1, 2, 5, 10)hydraulic diameters of the conduit.

The aperture 218 may be angled relative to a longitudinal axis of anentry region to the conduit, for example, if the conduit is cut at anangle rather than perpendicularly as shown in FIG. 3. That is, for acylindrical conduit, for example, the perimeter of the aperture 218 maybe an ellipse rather than a circle when the aperture 218 is angled. Forinstance, the planar orientation of the aperture 218 may be angled withrespect to the bottom 208 and/or the side wall 210 a in order to causethe flow of the liquid to change direction sufficiently as it flows fromthe inlet 202 and into the conduit 212 to inhibit swirl and gasentrainment.

The conduit 212 may be made of a variety of materials suitable forconveying the liquid of the closed-loop system without contaminating theliquid or reacting with the liquid. The liquid may be, for example, aliquid coolant such as, by way of example, distilled water, ethyleneglycol, propylene glycol, and mixtures thereof, or oil. The conduit 212may be rigid, e.g., stainless steel, polyvinylchloride (PVC) pipe, ormay be flexible, e.g., silicone or vinyl tubing, including with abraided sleeve.

The aperture 218 may be funnel-shaped, e.g., wider than a diameter ofthe conduit 212 at an outer edge and narrowing to the diameter of theconduit 212. The aperture 218 may also be fluted, e.g., have ridges orgrooves, which may further direct the liquid flow and inhibit flowseparation and cavitation at the aperture.

Accordingly, the shape and positioning of the conduit 212 may inhibit orreduce cavitation. Alternatively, or in addition, the shape andpositioning of the conduit 212 may at least move a cavitation zone awayfrom the pump, to the extent that cavitation is not completelyinhibited.

FIG. 4 shows an isometric view of an embodiment of a reservoir tank 300.As shown, the tank 300 has an inlet 302 positioned in a side wall, e.g.,side wall 310 b, above a free surface 301 of the liquid, instead of inthe top 304, although the inlet 302 could be positioned in the top 304or below the free surface 301 of the liquid. The tank 300 also has anoutlet aperture 306 through which a conduit 312 passes or to whichconduit segments attach, analogously to the conduits described inrelation to FIG. 3. The outlet aperture 306 may be positioned,alternatively, in the floor, a different side wall, at an edge or in acorner of the tank. The conduit 312 may be curved so that the apertureof the conduit is oriented to face the bottom 308 of the tank.

The tank 300 may also have a baffle 320 positioned in the tank. In FIG.4, the baffle 320 is oriented vertically in the tank relative togravity. In particular, the illustrated baffle extends from one interiorwall to another, opposed interior wall. In FIG. 4, the baffle 320 isoriented parallel to a selected pair of opposed walls and transverselyto each remaining interior wall. Of course, the baffle 320 may beselectively oriented relative to each of the walls and the baffle 320 isillustrated as being planar, though it need not be planar.

The baffle 320 may include a number of apertures through which theliquid can flow. The baffle 320 may be positioned between the inlet 302and the outlet 306. Each of the apertures in the baffle 320 has ahydraulic diameter. The hydraulic diameter (DO of a conduit or otherflow path is, generally, proportional to a ratio of the cross-sectionalarea (A) of the conduit or other flow path to the wetted perimeter (P)of the cross-section, i.e., D_(h)=4A/P. For a circular tube, thehydraulic diameter is simply the inside diameter of the tube.

The baffle 320 may extend, for example, from one side wall to anopposing side wall, and from the floor to above the free surface of theliquid, such that all liquid from the inlet 302 must flow through thebaffle 320 to reach the outlet 306 (or at least the entrance to theconduit 312). Alternatively, the baffle 320 may extend or be positionedsuch that some liquid can pass from the inlet to the outlet around anoutside perimeter of the baffle, for example, through a gap between thebaffle and a sidewall, through a gap between the baffle and the floor,or through a gap between the baffle and the free surface 301 of theliquid.

The use of a baffle 320 may inhibit entrainment of the gas present inthe top of the tank, i.e., above the free surface 301. The hydraulicdiameter of the apertures in the baffle 320 may be generally muchsmaller than the cross-sectional area of the liquid-filled part of thetank. The small-area apertures through the baffle (e.g., as defined by awire or other mesh) may disrupt swirling flows having a characteristicdimension on the order of a hydraulic diameter of the conduit 312inducing disorganized, small-scale swirling flows and enhancing mixingof the liquid in the reservoir as it flows from the inlet to the outlet.

As noted, the flow of the liquid from the inlet 302 toward the outlet306 must pass through small flow paths, e.g., through apertures in thebaffle, through small gaps positioned around the baffle, or both. Theapertures may change a direction of flow, at least locally (e.g., inregions adjacent the baffle), thus disrupting the potential for a vortexto form. The top of the baffle 320 may extend above the maximum liquidlevel 301 as shown, or may be positioned at or below the maximum liquidlevel 301.

FIG. 5 shows an example of a baffle 420 in a side-elevation view on theleft and in a front plan view on the right. The baffle 420 may be anexample of the baffle 320. The baffle 420 may have a height H, a widthW, and a thickness T. The height H may be selected to be at least ashigh as the intended depth of the liquid of the tank at the free surface301. However, since the liquid level of the tank may vary somewhat withthe conditions of the system, the height H of the baffle 420 may belarger than a maximum intended or likely liquid depth, and may be closeto, or the same as, the total inside height of the tank. The height Hmay be approximately the same as a maximum intended liquid level heightof the tank. In some instances, the baffle may be vertically oriented inthe tank and spaced apart from the bottom 308 such that the baffleextends partially above the maximum liquid level height and does notcontact the bottom of the tank.

The width W of the baffle 420 may be selected such that the baffle spansthe tank from one side wall to an opposing side wall. The width W neednot completely span the width of the tank, and the bottom of the baffle420 need not contact the bottom of the tank, so long as the baffle 420is retained in a selected position and orientation, and prevented frommoving out of position. Some liquid flow around the outer edges, outsideof the apertures, may be permissible as such flow may not be likely tocause or allow entrainment of a gas or induce a swirling flow having acharacteristic diameter on the same order of size as the hydraulicdiameter of the conduit. Generally, the width W of a baffle may besubstantially constant along its height, although in some cases, thewidth may vary, e.g., the baffle may be tapering, or undulating, forexample, if the side walls of the tank are not substantially parallelwith each other.

As shown, the baffle 420 has a plurality of rectangular apertures, eachhaving a height h and a width w, as well as a length T. The hydraulicdiameter of an aperture 422 is, accordingly, 4(w*h)/2(h+w). If h=w, thenthe hydraulic diameter is simply h. As shown, the apertures all have thesame hydraulic diameter. However, in other examples, the apertureswithin one baffle may have different respective hydraulic diameters. Theapertures may be arranged in a pattern, e.g., in increasing diameterfrom a center of the baffle radially outward, in increasing diameterfrom the top of the baffle to the bottom (or from the bottom to the top,left to right, or right to left), alternating rows, columns, or rings ofrelatively large diameters with relatively smaller diameters, and soforth. In still other examples, the apertures may be randomly orpseudo-randomly arranged, e.g., with no specific or discernable pattern.As well, although rectangular apertures 422 are illustrated, theapertures need not be rectangular. Rather, they may be circular,elliptical, rhomboid, or any other regular or irregular shape.

The baffle 420 may include a frame 424. The frame 424 may define aperimeter extending around the apertures 422 and provide structuralsupport to prevent the baffle from folding, bending, or otherwisedistorting in the liquid flow. The frame 424 may also provide apermanent or detachable means of fixing the baffle to the tank. Forexample, the frame 424 may fit inside and/or be held by clips, clasps,tracks, rails, springs or other fastening mechanisms in the tank itself.The frame 424 may, alternatively, be made of a material or be coated ina material, e.g., silicone or rubber, that hold the baffle in place viafriction between the frame and the sidewalls. The frame 424 may benaturally wider than the inside width of the tank, but sufficientlycompressible, e.g., resiliently compressible, to be placed in the tank,and allowed to decompress such that it urges against and stays fixed tothe side walls in a compressed arrangement with the side walls.

The baffle 420 may be made from a variety of materials, including, butnot limited to, plastic, steel, stainless steel, polymerized rubber, andaluminum. The baffle 420 may include a woven mesh or screen defining theapertures 422, in which case a thickness T of the baffle 420 may benegligible, e.g., a flow length of the apertures 422 may be negligible.The baffle 420 may be made from expanded metal in another embodiment.The baffle 420 may be extruded or 3-D printed plastic. In addition tosquares or rectangles, other cross-sectional shapes are possible,including as discussed with respect to FIG. 13.

FIG. 6 shows an embodiment using two vertically oriented baffles 520 aand 520 b. In an example, the hydraulic diameter of the apertures in thebaffle 520 a may be different from the hydraulic diameter of theapertures in the baffle 520 b. Alternatively, the hydraulic diameters ofthe apertures in each baffle may be the same. When the respectivehydraulic diameters of the baffles differ, the flow of the liquid fromthe inlet to the outlet may be disrupted differently by each baffle,further reducing the ability of a large vortex or other large-scaleswirling flow to form.

The baffles 520 may be separated by a distance k. The baffle closest tothe exhaust aperture 518 may be separated from the aperture, e.g., froma midpoint or center of the aperture, by a distance m. The distances kand/or m may be selected based on the hydraulic diameter(s) of theapertures 422 in each baffle 520 a, 520 b and the exhaust aperture 518,a flow rate of the liquid, and/or the thickness of the baffles.

FIG. 7 shows an alternative example where a baffle 620 is horizontallyoriented relative to gravity so that the baffle 620 is parallel to thebottom of the tank, but still positioned between the inlet and theoutlet of the tank. In such an example, the baffle 620 may havesufficient thickness T and/or have a cross-sectional shape to direct theflow of water through the apertures downward without generating avortex. For instance, apertures through the baffle 620, as withapertures through any baffle described herein, may be slanted ororiented transversely relative to a plane of the baffle. As well,adjacent apertures through the baffle need not be oriented in the samedirection. Rather, the A plurality of baffles may also be used, as inFIG. 6, where at least one of the baffles is horizontally oriented as inFIG. 7.

In some cases, a combination of differently oriented baffles may beused, for example, a horizontal baffle and a vertical baffle, or a firstbaffle oriented at a first angle from a vertical orientation and asecond baffle oriented at a second different angle from a verticalorientation where the two baffles are not orthogonal to each other.Other orientations may be used, for example, orientations that keep thebaffle oriented generally orthogonally to the flow of the liquid.

FIG. 8 shows a top-down view of a tank where three vertically orientedbaffles 720 a-c are used. As shown, the baffles 720 do not extend theentire width of the tank, allowing some of the liquid from the inlet 702to flow to the outside of the baffles 720 through a gap 721 between aperimeter of the baffles and an adjacent side wall of the enclosurebefore reaching the outlet 706. In other examples, the baffles 720 mayspan the distance between the side walls fully. The hydraulic diameterof the apertures of baffle 720 a may be different than the hydraulicdiameter of the apertures in baffle 720 b, which may be different thanthe hydraulic diameter of the apertures in baffle 720 c. In an example,the baffles 720 may be arranged in order of decreasing hydraulicdiameter from the inlet 702 to the outlet 706. Alternatively, thebaffles may be arranged in order of increasing hydraulic diameter fromthe inlet to the outlet. The baffles may be arranged such that thechanges in velocity of the flow inhibit entrainment and cavitation. Aswell, the apertures through the baffles 720 a-720 c need not be alignedwith each other or oriented perpendicularly to a plane defined by thecorresponding baffle. Rather, some or all of the apertures in a givenone of the baffles may be slanted (e.g., oriented transversely but notperpendicularly) relative to the plane defined by the respective baffle.Alternatively, the baffles may be oriented in a slanted fashion relativeto one or more side walls of the enclosure, as shown by way of examplein FIG. 9.

FIG. 9 shows a top-down view of a tank where three baffles arepositioned vertically and oriented at a non-perpendicular angle relativeto the side walls. Such an arrangement may allow the use of a bafflewith a larger surface area relative to a baffle arranged perpendicularlyas in FIG. 8. When the thickness T of the baffle is non-negligible, theorientation of the apertures may change the direction of the liquid flowaway from a direct flow from inlet 802 to outlet 806, as shown by thearrows, which may further inhibit or prevent entrainment. Eachrespective baffle may change the direction of the liquid flow to adifferent direction than an adjacent baffle, enhancing mixing of theliquid as it passes through the tank.

FIG. 10 shows a top-down view of a tank where a curved baffle 920 isused in a vertical orientation. The baffle may be curved convexly towardthe outlet 906 as shown, or may be curved concavely toward the outlet(not shown). The apertures in the curved baffle may be oriented radially(e.g., perpendicularly to a surface of the baffle) such that the flow ofthe liquid through the baffle disperses or converges somewhat as shownby the arrows, which may disrupt flows that might entrain the gas.Additional curved or non-curved baffles may be used in combination.

FIG. 11 shows a top-down view of a tank having a singular circular orovoid side wall 1010, and where two baffles 1020 a, 1020 b are used. Theapertures in one of the baffles 1020 may have the same hydraulicdiameter as the apertures in the other of the baffles, or may havediffering hydraulic diameters. Further, the baffles need not be parallelto each other.

FIG. 12 shows a top-down view of a cylindrical tank. The outlet 1106 canbe positioned on the bottom of the tank, as a drain. Alternatively, aU-shaped snorkel (not shown) can attach to the outlet 1106 and extendinwardly of the enclosure, such that an entrance to the snorkel requiresa change in flow direction as the liquid flows from the inlet 1102 tothe outlet 1106, as with the snorkel shown in FIG. 3. The baffle 1120may be circular, ovoid, rectangular, semispherical or have any othershape that extends around the outlet 1106 (or snorkel) to disrupt a flowof the liquid. In an example, the baffle may be centered on the outlet1106. Alternatively, the baffle 1120 may have its center offset from thecenter of the outlet 1106. The apertures in the baffle 1120 may beconfigured to prevent or inhibit a swirling liquid flow from forming.For example, some of the apertures may be blocked, or the apertures maybe oriented to direct the flow of the liquid away from the outlet 1106,or at least not directly radially toward or circumferentially around theoutlet 1106.

The examples are not limited to the illustrated examples above of tankshapes and baffle configurations. More or fewer baffles may be used. Theshape of the apertures of one baffle may differ from the shape of theapertures of another baffle, and may or may not have the same hydraulicdiameter. Two or more baffles used in one tank may have differentthicknesses. When three or more baffles are used in one tank, they maybe spaced apart equidistantly, or may have varying separation distances.

A tank may be a spherical tank. In a spherical tank, references to aside wall, top and bottom may be interpreted to refer to the portions ofthe sphere in relation to its position with respect to the ground orfloor of its environment. That is, the bottom may be the part of thesphere closest to the floor, the top is the portion of the sphereopposite the bottom, and the sidewall may be the portions of thespherical surface between the top and bottom. Naturally, other shapes oftanks are possible and known, and the concepts described herein can beincorporated in such tanks without departing from principles describedherein.

FIGS. 13A-C show examples of baffle apertures. Baffles may have, forexample and without limitation, hexagonally shaped apertures as in FIG.13A, circular apertures as in FIG. 13B, or rhomboid apertures as in FIG.13C. The walls of the apertures may be relatively thick with respect tothe hydraulic diameter, as in FIG. 13A, or may be thin relative to thehydraulic diameter, as in FIG. 13C. The examples are not limited to theillustrated shapes.

FIG. 14 shows an example of a series of baffles 1320 a, 1320 b, 1320 cwith offset apertures 1322. As liquid passes through the offsetapertures, streamlines through one aperture 1322 (e.g., in baffle 1320a) diverge and the flow from that aperture passes through, for example,two different apertures through an adjacent baffle (e.g., baffle 1320b). Such breaking apart of streamlines encourages liquid mixing andinhibits or prevents formation of large-scale flow structures (e.g.,swirling flows, vortices, etc.) that may entrain gas or inducecavitation. The cascading arrows illustrate such breaking apart ofstreamlines and mixing.

The apertures 1322 may have the same hydraulic diameter. Alternatively,the apertures of a baffle, e.g., baffle 1120 a, may have a differenthydraulic diameter than the apertures of another baffle, e.g., baffle1320 b. The baffles 1320 may be arranged such that the apertures 1322 ofone baffle do not align with the apertures of an adjacent baffle. Thismay disrupt the flow of the water, as shown by the arrows, sufficientlyto inhibit entrainment or cavitation.

In some cases, the baffles may also inhibit or reduce cavitation. Thebaffles affect the flow direction and the flow speed and thus may alignflow stream lines to reduce or eliminate pressure differentials that arecreated when the liquid flows from the relatively larger volume of thereservoir into the relatively smaller volume of the aperture, outlet andliquid conduit.

Fill Kit and Control Logic for Automated Filling of a Closed-Loop LiquidSystem

Closed-loop liquid systems, such as a liquid-based heat transfer systemor a hydraulic system, usually include a reservoir for the liquid, andone or more pumps to move the liquid from the reservoir to the othercomponents of the system through liquid conduits. After initialassembly, the pumps, conduits and reservoir usually contain gas, e.g.,air. The pumps are designed to move liquid through their impellers, andmay overheat or otherwise be damaged if operated while filled with a gasfor too long of a duration. Initially filling a closed-loop liquidsystem conventionally requires human intervention. Conventionally, asource of the liquid is connected to the system, e.g., to the reservoir,and the pumps are operated by a skilled technician to fill the systemgradually without burning out the pumps. For example, a technician mayturn the pumps on for a short period of time and then off, referred toas “bumping” the pump. The brief period of time that the pump operatesmay allow some liquid to be drawn into the conduits but withoutover-heating the pump. The off period may allow the pumps to cool ifheating has occurred. Repeatedly bumping the pumps eventually fills thesystem with the liquid. The gas in the system is usually allowed toescape, for example, by a valve positioned somewhere between the pumpsand a return to the reservoir. Human supervision has been necessary toensure that the pumps do not operate for too long of a period while dry,however, this can increase the costs to the owner of the closed-loopliquid system and/or may delay the start of using the system.

FIG. 15 shows a block diagram of an example of a fluid conditioning unit1400 as may be used in a closed-loop liquid system. The fluidconditioning unit 1400 may include a reservoir 1410, a pump 1420, aclosed-loop liquid operational component 1430 and control logic 1440.During an initial filling process, a fill tank 1450 and a fill pump 1460may be coupled to the fluid conditioning unit 1400.

The reservoir 1410 may be a tank configured to hold a liquid for theclosed-loop liquid system, e.g., a coolant, water, hydraulic fluid, oroil. The reservoir 1410 may have an outlet 1412 that is fluidicallycoupled to the pump 1420, e.g., with a hose, a pipe, tube or other fluidconduit. The reservoir 1410 may have an inlet 1414 that is fluidicallycoupled to the operational component 1430 to receive the liquid after ithas flowed through the system. When the system is filled to anoperational capacity, the reservoir 1410 may contain the liquid of thesystem and some amount of gas, such as, for example, air, to accommodatechanges in temperature, pressure and volume in the system while inoperation. Other than any inlets and outlets, the reservoir maygenerally be sealed to prevent or reduce evaporation and spills of theliquid contained by the reservoir.

The pump 1420 may be configured to move liquid from a pump inlet 1422through a pump outlet 1424 and urge the liquid from the pump to theoperational block 1430. The pump 1420 may be powered, e.g.,electrically, so that it can be started and stopped to activate anddeactivate the flow of liquid. Additionally, the speed of the pump 1420may be controllable, for example, by varying an amount of power suppliedto the pump or by a separate control signal (e.g., using avariable-frequency drive). The pump 1420 may be, for example, acentrifugal pump or a positive displacement pump.

The closed-loop liquid operational block 1430 represents a region of ageneral closed-loop liquid system where the liquid or a flow of theliquid performs a function. In one embodiment, the closed-loop liquidsystem is a heat-transfer system that absorbs heat from one or more heatsources and dissipates the heat to one or more heat sinks.

For example, in a liquid-cooled heat exchange system, the operationalblock 1430 may represent, at least, fluid conduits containing a liquidcoolant, heat exchanger components in thermal contact with the fluidconduits, and/or heat dissipating elements. For example, in theoperational block 1430, a heat exchanger may be in thermal contact witha heat-dissipating element, such as a processor. Energy may conduct(e.g., diffuse) from the walls of the heat exchanger into adjacent fluidparticles of a liquid coolant within the fluid conduits, and theadjacent fluid particles are swept away from the wall, or advected,carrying the energy absorbed from the walls. The swept-away particlesare replaced by other, usually cooler fluid particles, which morereadily absorb energy from the walls (e.g., by virtue of their usuallylower temperature). Such a combination of conduction and advection(i.e., convection) provides an efficient approach for cooling deviceshaving a relatively high heat flux, such as, for example, electronicdevices. After passing through the plurality of passages in the heatexchanger, the heated liquid coolant may pass to another heat exchanger,carrying with it the energy absorbed from the first heat exchanger. Asthe heated coolant passes through the second heat exchanger, energy isrejected from the coolant (e.g., to another working fluid, such as, forexample, the air, or a building's water supply) through convectionprocesses similar to those described above. From the second heatexchanger, the cooled working fluid may be pumped back to the first heatexchanger.

The closed-loop liquid system may be a hydraulic system. For example, ina hydraulic system, the operational block 1430 may represent, at least,conduits and chambers where a hydraulic fluid is pressurized to apply aforce to a member. When the liquid has performed its function, it mayreturn to the reservoir 1410 at the inlet 1414.

The control logic 1440 (or any other control logic described herein) mayinclude instructions, e.g., stored on a memory, and a processing unitconfigured to execute the instructions. The control logic 1440 may becommunicatively coupled to the pump 1420. The control logic 1440 may,for example, be configured to start and stop the pump 1420. The controllogic 1440 may receive information from the pump 1420 or from a sensorobserving an operational parameter about the pump. Such sensors caninclude, among others, a temperature sensor so positioned relative to afluid as to provide a signal corresponding to a temperature of a fluidwithin the conduit or a temperature of a surface, a pressure sensor sopositioned as to provide a signal corresponding to a relative pressuredifference between a static pressure in a liquid and a selectedreference pressure, a speed sensor (e.g., a tachometer) configured toprovide a signal corresponding to a rotational speed of a pump, a floatsensor or other sensor configured to provide a signal corresponding to acoolant level in the reservoir, and a humidity sensor configured toprovide a signal corresponding to one or more of an absolute humidity, arelative humidity, a wet-bulb temperature and a dry-bulb temperature. Ingeneral, such a sensor can observe a thermodynamic quantity, or anoperational parameter indicative of a thermodynamic quantity.

The control logic 1440 may be communicatively coupled to the operationalblock 1430. The control logic 1440 may receive information from one ormore sensors within the operational block 1430. For example, thereceived information may include temperature, pressure, flow rate, or aliquid level at one or more points in the block, or any otherthermodynamic quantity relating to the flow or a condition of acomponent in the conditioning unit 1400, the pump 1460, or the fill tank1450.

The control logic 1440 may be communicatively coupled to the variouscomponents of the fluid conditioning unit 1400 through a wiredconnection, a wireless connection, or both. A communication bus may beconfigured to send and receive control signals and sensor information toand from a processing unit and/or memory of the control logic. Suchsignals can include any type of signal suitable for conveyinginformation, including wired and wireless signals, e.g., radio frequency(RF), infrared (IR), microwave and photonic signals.

During an initial filling operation, the fluid conditioning unit 1400may be connected to a fill tank 1450 and a fill pump 1460. The fill pump1460 may be fluidically coupled to the reservoir 1410, for example, at asupply inlet 1416 by a coupling. The coupling may be reversiblydetachable. The fill pump 1460 may be fluidically coupled to the filltank 1450 and may operate to pump liquid from the fill tank 1450 intothe reservoir 1410. The fill tank 1450 may hold an amount of liquidsufficient to fill the fluid conditioning unit 1400, including thereservoir 1410, while allowing some gas to remain in the reservoir.

In reference to a filling operation, the terms “enough,” “sufficient,”or “filled” may refer to an amount of liquid such that all of the liquidconduits and fluidically coupled components in at least the fluidconditioning unit, or in the entire closed-loop system between theoutlet of the reservoir and the inlet of the reservoir contain liquidand only a negligible amount of gas. A negligible amount of gas mayremain in the system in the form of, for example, micro-pockets of gaspresent because the surface tension of the liquid prevent the liquidfrom filling the pocket. The reservoir itself may contain liquid to aspecified level, with some amount of gas (e.g., to accommodate expansionand contraction of the liquid). In some cases, the terms may refer to anamount of liquid in the pump 1420 and upstream from the pump such thatthe pump can operate continuously without overheating, although the restof the system downstream from the pump may not yet be liquid-filled.

During the initial filling operation, the control logic 1440 may becommunicatively coupled to the fill pump 1460. This may allow thecontrol logic 1440 to start and stop the fill pump 1460 to maintainsufficient liquid in the reservoir while the rest of the fluidconditioning unit 1400 fills. Additionally, the control logic 1440 may“bump” the pump 1420 to move liquid from the reservoir through the restof the fluid conditioning unit 1400. During the initial fillingoperation, the control logic 1440 may use information received ormeasured about one or more operational parameters to determine whetherthe fluid conditioning unit 1400 is filled, without the need for humanintervention. An operational parameter that meets a threshold value mayindicate that a sufficient amount of liquid has moved through the pump1420 and the component 1430 to indicate that the system is filled.

The control logic 1440 may also be communicatively coupled to a valve(not shown) positioned between an outlet of the pump 1420 and the inlet1414 to the reservoir. The control logic 1440 may communicate a signalto the valve to cause the valve to open, to release gas from within thesystem.

When the initial filling operation is completed, the fill pump 1460 andfill tank 1450 may be decoupled from the reservoir 1410 and the controllogic 1440 may be communicatively decoupled from the fill pump 1460. Forexample, a coupling between the reservoir and the fill pump 1460 may bedetached, or a valve between the fill pump and the reservoir may beclosed. Communicatively decoupling the control logic from the fill pumpnay include, for example, closing a wireless communication channel,disconnecting a wired communication coupling, or turning off power tothe fill pump so that it is not capable of receiving, responding to, orsending communication signals.

According to an aspect, the fill pump 1460 can be omitted. For example,the fill tank 1450 can be elevated relative to the reservoir 1610. Asyphon can draw coolant into the reservoir. The remainder of the flowpaths throughout the fluid conditioning unit can be filled as describedelsewhere herein.

FIG. 16 shows a block diagram of a fluid conditioning unit 1500 used ina liquid-cooled heat exchange system. The fluid conditioning unit 1500may include one or more pumps, e.g., pumps 1520-1 to 1520-n, where nrepresents a positive integer. Heated coolant may be cooled in the heatexchanger 1530 before being provided to a heat transfer element 1580.The heat transfer element 1580 may represent one or more devices orsystems that dissipate heat to the coolant. The warmed coolant isreturned to the reservoir 1510.

The fluid conditioning unit 1500 may include one or more sensorspositioned in various parts of the system. For example, each pump 1520-1. . . 1520-n may have an associated sensor 1570-1 . . . 1570-n, whereeach respective sensor 1570 may observe or detect an operationalparameter related to the pump or to the liquid outflow from the pump,such as, for example, flow rate, temperature, pump speed, or pressure. Asensor 1572 may be associated with a supply line conduit carrying liquidout from the heat exchange component 1530. The sensor 1572 may, forexample, detect or observe temperature, pressure or flow rate in thesupply line. A sensor 1573 may be associated with the reservoir 1510 andmay detect or observe, for example, a liquid level, a liquid mass, aliquid volume, and/or a liquid temperature for the liquid in thereservoir. More, fewer, or other sensors may be used in the system.

Information detected or observed by the sensors 1570, 1572, 1573 may becommunicated to the control logic 1540. During an initial fillingoperation, the control logic 1540 may use the received information todetermine whether the fluid conditioning unit 1500 is filled. In anembodiment, the control logic 1540 may rely on a single operationalparameter, for example, a pressure measurement from the sensor 1572 todetermine that the fluid conditioning unit 1500 is filled. A pressuremeasurement from the sensor 1572 that meets a threshold value mayindicate that a sufficient amount of liquid has moved through the pumpsand the component 1530 to exert the pressure at the sensor 1572,indicating that the system is filled. In another embodiment, the controllogic 1540 may use a combination of sensor information to make thatdetermination. For example, the pressure from the sensor 1572 and aliquid level measurement from the sensor 1573 may be used. While theremay be sufficient liquid in the fluid conduits in the fluid conditioningunit 1500, the reservoir may not yet be filled to its specifiedcapacity, indicating that more liquid needs to be added to the system.However, once the pressure and the liquid level have both reached aspecified value, the control logic 1540 may determine that the fillingoperation is complete.

In still another embodiment, once information from a sensor or sensorsindicates that the fluid conditioning unit 1500 may be full, the controllogic 1540 may wait for a period of time to determine whether thatinformation changes or remains sufficiently constant. For example, apressure reading may temporarily match a threshold but drop below thethreshold as gas bubbles or pockets move past the sensor, indicatingthat the system is not yet full.

The control logic 1540 may be configured to operate the pumps 1520 andthe fill pump 1560 during a filling operation. For example, the controllogic 1540 may start the fill pump 1560 until the sensor 1573 indicatesthat a specified liquid level or mass is reached in the reservoir 1510.The control logic 1540 may then stop the fill pump 1560 and start one ormore of the pumps 1520 briefly. The pumps may be started and stopped oneat a time, or in parallel. The control logic 1540 may start a pump 1520for a time period that pumps liquid from the reservoir but does notcause the pump to overheat. That time period may be dependent on thespecification of a given pump. Examples of the time frame may be on theorder of less than a minute, e.g., 5, 10, 25, 30, 40, or 55 seconds, toabout 1-3 minutes, e.g., 1.5 minutes, 2.25 minutes.

In an embodiment, once sensor information, e.g., from the sensors 1570,indicates that the pumps 1520 are liquid-filled, even if the conduitsdownstream from the pumps are not completely filled, the control logic1540 may allow the pumps 1520 to run continuously until other sensorinformation indicates that the fluid conditioning unit 1500 is filled.

The control logic 1540 may continuously receive sensor informationpushed from the sensors, or may request and pull information at specificintervals, e.g., every 2 seconds or every 10 seconds, or after specificevents, such as, for example, after a pump has been “bumped”.

In some embodiments, the fluid conditioning unit 1500 may include valves1582 at the outlet(s) of the reservoir 1510. The valves 1582 may beone-way valves that allow liquid to leave the reservoir at the outlets,but do not allow liquid to enter the reservoir at the outlets. The fluidconditioning unit 1500 may also include a valve 1584 and a bypassconduit that allows liquid from the pumps to return to the reservoir,for example, when an outlet from the pump is blocked, a conditionreferred to as a “dead head.” A dead-headed pump, if allowed to continueto pump, may heat the liquid trapped within it, eventually damaging thepump. If the inlet(s) to the heat exchanger 1530 are blocked, forexample, the valve 1584 may be opened to allow the liquid from the pumpsto return to the reservoir.

Referring again to FIG. 1C, a block diagram of a liquid-cooled heatexchange system having a fluid conditioning unit 1600 as may be used ina rack to cool servers in the rack is shown. The fluid conditioning unit1600 can be mounted in a rack, or fluidically coupled to a rack, and maycirculate cooling liquid among a plurality of rack-mounted serversystems. The fluid conditioning unit 1600 may further facilitatetransfer of the heat absorbed from the servers to another coolant, e.g.,facility water. Some rack-mountable server systems include a rack 1650holding a plurality of independently operable servers (not shown). Theliquid-cooled heat exchange system can have a plurality of branches,where a branch can be configured to convey a liquid, e.g., a coolant,from an inlet to the branch to an outlet from the branch. The inlet andthe outlet can be fluidly coupled with a liquid supply, such as adistribution manifold 1652, and a liquid collector, e.g., a collectionmanifold 1654, respectively. A given branch may convey the liquid to aheat transfer element thermally coupled to one or more heat dissipatingdevice, e.g., memory, chipsets, microprocessors, hard drives, etc. Heatfrom the heat dissipating device is transferred from the device to theliquid passing through the heat transfer element. The heated liquidexits the branch at the outlet. A branch may cool one or more heatdissipating devices in one server on the rack. For example, a givenserver may have more than one processing unit that needs to be cooledduring operation, and a corresponding heat transfer element can have oneheat-transfer module for each processing unit in the server. Thedistribution manifold 1652 and the collection manifold 1654 may beintegral to the rack or may be separate and couplable to the rack.Examples of a liquid-cooled heat exchange system used to cool servers ina rack are disclosed in commonly-owned U.S. Pat. No. 9,496,200, which isincorporated by reference herein in its entirety.

The fluid conditioning unit 1600 may be installed on or in the rack1650, e.g., generally as depicted in FIG. 1A. Alternatively, theconditioning unit may be a stand-alone conditioning unit fluidicallycoupled with a plurality of rack mounted servers. In either arrangement,the unit 1600 may operate to cool the liquid from the collectionmanifold 1654. For example, warm liquid from the collection manifold1654 may enter the reservoir 1610 and be pumped from the reservoir to aheat exchanger 1630 by one or more pumps 1620. The heat exchanger 1630may be, for example, a plate heat exchanger, a cross-flow or acounterflow liquid-liquid heat exchanger. The heat exchanger 1630 mayreceive chilled system liquid, e.g., chilled water, through an inletconduit 1632 from an external environment heat exchanger 1660. The heatexchanger 1630 transfers heat from the warm liquid received from thereservoir to the chilled system liquid from the environmental heatexchanger 1660. The warmed system liquid returns to the environmentalheat exchanger 1660 at the outlet 1634. The environmental heat exchanger1660 may then transfer the heat from the system liquid to theenvironment or to another heat-transfer system.

Alternatively, the heat exchanger 1630, or an additional heat exchanger,may be positioned between the collection manifold and the reservoir, tocool the liquid as it leaves the collection manifold, before it isreturned to the reservoir or to other system components (not shown).

The now-cooled liquid within the closed loop in the heat exchanger 1630may be conveyed to the distribution manifold 1652 ready to be used tocool components within the branches.

In an embodiment, the branches of the liquid-cooled heat exchange systemthat are within the rack 1650 may be delivered to a site already filledwith the cooling liquid. The collection and distribution manifolds mayalso be pre-filled. In these embodiments, the fluid conditioning unit1600 may be used to fill the reservoir 1610, pumps 1620, the heatexchanger 1630, and the conduits therebetween without having to fill therack or manifolds.

In still another embodiment, the fluid conditioning unit 1600 may beused to fill the liquid conduits and other heat exchange systemcomponents of the rack 1650, the distribution manifold 1652, and/or thecollection manifold 1654. In such an embodiment, the control logic 1640may receive information from sensors positioned in one or more of therack 1650, the distribution manifold 1652, and/or the collectionmanifold 1654 to determine when the system components are filled. Thecontrol logic 1640 may control pumps within the rack 1650 directly, orindirectly via control logic that may be present within the rack, to“bump” them during an initial filling operation as described above.

FIG. 17 shows a logic flow diagram 1700 such as one that may be executedby the control logic 1440, 1540, or 1640 in a fluid conditioning unithaving a pump, during an initial filling operation.

In an embodiment, the logic flow 1700 may activate a pump for aspecified duration in block 1702, e.g., a pump 1420, 1520, or 1620. Thecontrol logic may turn the pump on, e.g., with a switch, or may startthe pump motor such that the motor pumps fluid from the reservoir.Initially, the fluid may be gas present in the conduit connecting thepump to the reservoir. The control logic may then stop the motor, turnthe pump off, or otherwise prevent the pump from pumping after specifiedduration. Generally, the specified duration may be a brief period, forexample and without limitation, on the order of less than a minute,e.g., 5, 10, 25, 30, 40, or 55 seconds, to about 1-3 minutes, e.g., 1.25minutes, 2.75 minutes.

The logic flow 1700 may receive a signal from a sensor in block 1704.The control logic may pull information from a sensor, or may retrievesensor information pushed from a sensor from a memory or a communicationbus.

The logic flow 1700 may determine whether the filling operation iscompleted in block 1706, e.g., whether the system is “filled” or whetherthere is “enough” liquid in the system to permit the pumps to runcontinuously. In reference to a filling operation, the terms “enough,”“sufficient,” or “filled” may refer to an amount of liquid such that allof the liquid conduits and fluidically coupled components in at leastthe fluid conditioning unit, such as, for example, pumps and heatexchangers, or in the entire closed-loop system between the outlet andthe inlet of the reservoir, contain liquid and only a negligible amountof gas. The reservoir itself may contain liquid to a specified level,with some amount of gas. Alternatively, the terms may refer to an amountof liquid in the pumps and upstream from the pumps such that the pumpscan operate continuously without overheating.

Returning to block 1706, in an embodiment, the control logic may comparethe received sensor information to a threshold value. When the sensorinformation meets a threshold indicating sufficient liquid, then thecontrol logic may determine that there is enough liquid in the systemand that the system is filled. In another embodiment, the control logicmay use the sensor information to calculate a second value, for example,as a function of the sensor information, to determine if the systemcontains enough liquid. For example, and without limitation, a sensormay provide a volume reading of the liquid, and the control logic maycalculate a pressure based on the volume and then compare the pressureto a threshold. The calculation of a second value may use informationfrom other sensors, depending on the variables of the function.

Additionally, or alternatively, the control logic may determine whetherthe filling operation is completed based on information from more thanone sensor, and/or from information from a sensor obtained at differenttimes.

When the filling operation is not completed, the logic flow 1700 mayrepeat, beginning at block 1702. When the filling operation iscompleted, the logic flow 1700 may perform other operations at block1708. For example, a fill pump and/or the pumps 1420, 1520, 1620 may bedeactivated, the fluidic coupling between the fill pump and thereservoir may be decoupled, and/or the communication coupling betweenthe control logic and the fill pump may be decoupled.

Self-Diagnosis

As yet another example, the second value may be a value of athermodynamic state variable for a given substance in the system (e.g.,a coolant flowing among the various components in any of the heattransfer systems described herein). A number of sensors arrangedthroughout the system may measure selected physical characteristics of,for example, a coolant flowing among a plurality of rack mounted serversand a fluid conditioning unit. A number of other sensors arrangedthroughout, e.g., a rack of servers, also may measure selected physicalcharacteristics of components that interact with the heat transfersystem. Such characteristics may include, without limitation, processorpower dissipation (e.g., energy per unit time). A physical model maydescribe an inter-relation between or among such physicalcharacteristics, as through an equation of state. Consequently,measurements of selected physical quantities by selected sensors can beinput into a model (e.g., an equation of state) and that model canpredict values of selected physical quantities, e.g., at a selectedposition within the heat-transfer system. Control logic can implementsuch modeling technologies.

Predictions of selected physical quantities can be compared tomeasurements of those physical quantities. If the prediction fallswithin a selected threshold difference from the measured quantity (orvice-versa), the sensor that observed the measured quantity may beassumed to be in good working order. However, a failing or a failedsensor may be identified if the prediction differs from the measuredquantity by more than a selected threshold difference. For example, oneof the sensors used to generate the prediction and/or the sensor used toobserve the physical quantity to which the prediction is compared may befaulty. By inputting a quantity measured by a faulty sensor to anequation of state or a comparison to a predicted value of a statevariable, the predicted value and the measured value likely will differby more than a selected threshold difference. Such a difference may giverise to a presumption that a sensor is faulty. Further comparison amongpredicted and observed values throughout the system can be used toidentify which sensor(s) may be faulty. Control logic can implement suchcomparison technologies.

Prediction and comparison technologies described herein can allow systemcomponents, including, by way of example and not limitation, fluidconditioning units to “self diagnose” system and component health. Forexample, a failing pump, a leak, an excessive heat-dissipation, a poorthermal coupling, and any of a variety of other system degradations orfaults may be identified with techniques described herein. Control logiccan implement such self-diagnosis technologies. Moreover, when a faultor other degradation is determined, control or other logic can emit aflag or otherwise emit an alert or other signal indicating the presenceof the fault or other degradation.

By way of further explanation, an equation of state is a thermodynamicequation relating state variables of matter, which describe the state ofa given substance under a given set of physical conditions. For example,pressure (p), volume (V), and temperature (T) are state variables, as isinternal energy. Many state variables are known, and each quantifies arespective characteristic of matter throughout the various thermodynamicstates of that matter. In general, equations of state are useful fordescribing properties of matter, including fluids, mixtures of fluids,and solids.

As a general principle, pressure, volume and temperature for a givenamount of matter are not independent of each other. Rather, they arelinked by a relationship generally of the form f(p,V,T)=0. An equationused to model that relationship is generally referred to in the art asan equation of state.

Many equations of state have been developed and may be used inconnection with technologies described herein. One useful equation ofstate used to model so-called “incompressible liquids” is V=constant.Stated differently, the general form of the equation of state can bereduced to a two-variable equation of state: f(p,T)=0 when the volume ofa given substance (e.g., an “incompressible” liquid) remains constant,or approximately constant over a selected range of temperatures and aselected range of pressures. Coolants of the type described herein, intheir liquid phase, typically can be reliably modeled as beingincompressible. Nonetheless, technologies described herein are notlimited solely to incompressible liquids. Rather, technologies describedherein can be applied to incompressible and compressible fluids, andsaturated mixtures thereof, as well as solids and saturated solid-liquidmixtures.

For example, a variety of temperature, flow-rate, and/or pressuresensors can be arranged within any of the heat-transfer systems (andcomponents thereof) described herein. Such sensors can be arranged toobserve, for example, temperature, flow-rate and pressure (e.g., staticand/or stagnation) at one or more selected locations within a fluidcircuit (open or closed), or any other physical characteristicpertaining to a thermodynamic state of a substance in the heat-transfersystem. A controller (e.g., control logic) can adjust operation of oneor more coolant (e.g., a pump, a valve) and/or heat-transfer components(e.g., a logic or other component of a computing environment) to achievedesired flow and/or cooling characteristics within the heat-transfersystem.

As another example, measurement of observable state-variables (e.g.,temperature, static pressure, mass, density) combined with knownmeasures of selected properties (e.g., specific heat, heat capacity,compressibility, gas constant, equation-of-state) of a given fluidand/or observable system performance characteristics (e.g., powerdissipation from a heat source), health and robustness of system sensorscan be assessed and communicated to a system user or manager. Forexample, some disclosed systems, controllers and methods can computevalues of state variables at one or more selected locations within aselected fluid circuit (or branch thereof) and compare the computedvalue to an observed value detected from a given sensor.

If an absolute value of a difference between the computed value and theobserved value exceeds a selected threshold difference, an innovativesystem, controller or method can determine a fault has occurred and cantake a remedial action, as by setting a flag, sending an e-mail, and/orinitiating an alarm to alert a user of the determined fault. Such afault can indicate a failed or failing sensor, a leak, an overtemperature condition, a failed pump, an under-speed pump, an over-speedpump, a failed or failing controller.

Computing Environments

FIG. 18 illustrates a generalized example of a suitable computingenvironment 1800 in which described methods, embodiments, techniques,and technologies relating, for example, to control of a fillingoperation and other system control for a liquid-filled closed loopsystem. The computing environment 1800 is not intended to suggest anylimitation as to scope of use or functionality of the technologiesdisclosed herein, as each technology may be implemented in diversegeneral-purpose or special-purpose computing environments. For example,each disclosed technology may be implemented with other computer systemconfigurations, including wearable and handheld devices, multiprocessorsystems, microprocessor-based or programmable consumer electronics,embedded platforms, network computers, minicomputers, mainframecomputers, smartphones, tablet computers, data centers, audio devices,and the like. Each disclosed technology may also be practiced indistributed computing environments where tasks are performed by remoteprocessing devices that are linked through a communications connectionor network. In a distributed computing environment, program modules maybe located in both local and remote memory storage devices.

The computing environment 1800 includes at least one central processingunit 1810 and memory 1802. In FIG. 18, this most basic configuration1803 is included within a dashed line and may represent the controllogic, e.g., control logic 1440, 1540, or 1640. The central processingunit 1810 executes computer-executable instructions and may be a real ora virtual processor. In a multi-processing system, multiple processingunits execute computer-executable instructions to increase processingpower and as such, multiple processors can run simultaneously. Thememory 1802 may be volatile memory (e.g., registers, cache, RAM),non-volatile memory (e.g., ROM, EEPROM, flash memory, etc.), or somecombination of the two. The memory 1802 stores software 1808 a that can,for example, implement one or more of the innovative technologiesdescribed herein, when executed by a processor.

A computing environment may have additional features. For example, thecomputing environment 1800 may include storage 1804, one or more inputdevices 1805, one or more output devices 1806, and one or morecommunication connections 1807. An interconnection mechanism (not shown)such as a bus, a controller, or a network, interconnects the componentsof the computing environment 1800. Typically, operating system software(not shown) provides an operating environment for other softwareexecuting in the computing environment 1800, and coordinates activitiesof the components of the computing environment 1800.

The store 1804 may be removable or non-removable, and can includeselected forms of machine-readable media. In general, machine-readablemedia include magnetic disks, magnetic tapes or cassettes, non-volatilesolid-state memory, CD-ROMs, CD-RWs, DVDs, magnetic tape, optical datastorage devices, and carrier waves, or any other machine-readable mediumwhich can be used to store information, and that can be accessed withinthe computing environment 1800. The storage 1804 stores instructions forthe software 1808 b, which can implement technologies described herein.

The storage 1804 can also be distributed over a network so that softwareinstructions are stored and executed in a distributed fashion. In otherembodiments, some of these operations might be performed by specifichardware components that contain hardwired logic. Those operations mightalternatively be performed by any combination of programmed dataprocessing components and fixed hardwired circuit components.

The input device(s) 1805 may be a touch input device, such as akeyboard, keypad, mouse, pen, touchscreen, touch pad, or trackball, avoice input device, a scanning device, or another device, that providesinput to the computing environment 1800.

The output device(s) 1806 may be a display, printer, speaker transducer,DVD-writer, or another device that provides output from the computingenvironment 1800.

The communication connection(s) 1807 enable communication over acommunication medium (e.g., a connecting network) to another computingentity. The communication medium conveys information such ascomputer-executable instructions, compressed graphics information,processed signal information (including processed audio signals), orother data in a modulated data signal.

Thus, disclosed computing environments are suitable for performingdisclosed orientation estimation and audio rendering processes asdisclosed herein.

Machine-readable media are any available media that can be accessedwithin a computing environment 1800. By way of example, and notlimitation, with the computing environment 1800, machine-readable mediainclude memory 1802, storage 1804, communication media (not shown), andcombinations of any of the above. Tangible machine-readable (orcomputer-readable) media exclude transitory signals.

As explained above, some disclosed principles can be embodied in atangible, non-transitory machine-readable medium (such asmicroelectronic memory) having stored thereon instructions, whichprogram one or more data processing components (generically referred tohere as a “processor”) to perform the digital signal processingoperations of the control logic described above including estimating,adapting, computing, calculating, measuring, adjusting, sensing,measuring, filtering, addition, subtraction, inversion, comparisons, anddecision making. In other embodiments, some of these operations (of amachine process) might be performed by specific electronic hardwarecomponents that contain hardwired logic (e.g., dedicated digital filterblocks). Those operations might alternatively be performed by anycombination of programmed data processing components and fixed hardwiredcircuit components.

Other Exemplary Embodiments

Directions and references (e.g., up, down, top, bottom, left, right,rearward, forward, etc.) may be used to facilitate discussion of thedrawings and principles herein, but are not intended to be limiting. Forexample, certain terms may be used such as “up,” “down,”, “upper,”“lower,” “horizontal,” “vertical,” “left,” “right,” and the like. Suchterms are used, where applicable, to provide some clarity of descriptionwhen dealing with relative relationships, particularly with respect tothe illustrated embodiments. Such terms are not, however, intended toimply absolute relationships, positions, and/or orientations. Forexample, with respect to an object, an “upper” surface can become a“lower” surface simply by turning the object over. Nevertheless, it isstill the same surface and the object remains the same. As used herein,“and/or” means “and” or “or”, as well as “and” and “or.” Moreover, allpatent and non-patent literature cited herein is hereby incorporated byreferences in its entirety for all purposes.

The principles described above in connection with any particular examplecan be combined with the principles described in connection with any oneor more of the other examples. Accordingly, this detailed descriptionshall not be construed in a limiting sense, and following a review ofthis disclosure, those of ordinary skill in the art will appreciate thewide variety of cooling systems, controllers and methods that can bedevised using the various concepts described herein. Moreover, those ofordinary skill in the art will appreciate that the exemplary embodimentsdisclosed herein can be adapted to various configurations withoutdeparting from the disclosed principles.

For example, a disclosed system can include an enclosure having an inletto the enclosure and a wall at least partially defining a boundary ofthe enclosure. The enclosure can be configured to receive a liquid fromthe inlet and to contain the received liquid. An aperture can extendthrough the wall. A conduit can be coupled with the aperture, and theconduit can include a segment extending into the enclosure from theaperture. A baffle can define a corresponding plurality of apertures.The baffle can be positioned between the inlet and the segment of theconduit, and the baffle can be oriented such that liquid received fromthe inlet passes through the plurality of apertures in the baffle beforeentering the segment of conduit.

Each in the plurality of apertures in the baffle can be circular orpolygonal.

The baffle can include one or more of a screen, a mesh, and anexpanded-metal panel.

The baffle can be oriented transversely relative to the wall. Forexample, the baffle can be oriented orthogonally of a flow directionbetween the inlet and the segment of conduit. The baffle can be sooriented relative to a bulk flow direction between the inlet and thesegment of conduit as to turn a direction of flow adjacent the baffle.In some embodiments, the baffle is curved, and in others the baffle issubstantially planar.

The baffle can extend from a height above a maximum liquid level of thetank toward the bottom of the tank without contacting the bottom of thetank.

The system can also include a pump and conduit fluidly coupling the pumpwith the aperture in the wall. The aperture in the wall can be a firstaperture, and the inlet can be a second aperture in the wall.

Other system arrangements are possible. For example, a system caninclude a sealed tank having a top, a bottom, and a side wall. The tankcan be configured to receive a liquid from an inlet and to hold theliquid. A wall aperture can extend through the side wall. A liquidconduit can be coupled with the wall aperture at a first conduitaperture. The liquid conduit can define a second conduit aperture insidethe tank. The liquid conduit can also include bend, such that a firstdistance from the bottom of the tank to the second conduit aperture issmaller than a second distance from the bottom of the tank to a bottomedge of the wall aperture.

A plane of the second conduit aperture can be parallel to the bottom ofthe tank. The liquid conduit can be perpendicular to the side wall atthe wall aperture.

A baffle can have a plurality of apertures. Each aperture can have ahydraulic diameter. The baffle can be positioned between the inlet andthe second conduit aperture and the baffle can be oriented so that theliquid received from the inlet passes through the plurality of aperturesin the baffle before exiting the tank at the second conduit aperture.

A control system can include control logic comprising a processing unitand instructions stored on a memory that, when executed by theprocessing unit, cause the control logic to perform selected actions.Such actions can be combined. For example, the control logic cancommunicate a control signal to a pump in a fluid conditioning unit. Thecontrol logic can receive a signal from a sensor in the fluidconditioning unit. The control logic can iteratively activate anddeactivate the pump via the control signal until the signal receivedfrom the sensor comprises an indication that the fluid conditioning unitis filled with a liquid to a specified amount.

The control logic can activate the pump for a duration of less than oneminute, or about 1-3 minutes. The signal from the sensor can include avalue of an observational parameter. The control logic can compare thevalue of the observational parameter to a programmed value to determinewhether the signal comprises the indication.

The operational parameter can be at least one of: a temperature, apressure, a flow rate, a pump speed, a mass, a fluid level, a fluidvolume, a load on a pump, a specific volume, an enthalpy, a specificheat, and a combination thereof.

The control logic can calculate a value as a function of the value ofthe observational parameter to determine whether the signal comprisesthe indication.

The control logic can communicate a second control signal to a valve inthe fluid conditioning unit. The valve can be configured to release gasfrom the fluid conditioning unit.

The control logic can open the valve via the second control signalresponsive to the signal received from the sensor.

A system can include a reservoir defining an inlet and an outlet, andthe reservoir can be configured to hold a liquid received from theinlet. The pump can have a pump outlet and a pump inlet, where the pumpinlet is fluidically coupled to the reservoir outlet by a first liquidconduit. The pump can be configured to pump the liquid from thereservoir through the pump outlet to a second liquid conduit.

A fill tank can be configured to fluidically couple to the inlet of thereservoir; and a second pump can be configured to pump liquid from thefill tank to the reservoir.

The control signal to the pump can be a first control signal to thefirst pump, and the control logic can communicate a second controlsignal to the second pump.

The second liquid conduit can be fluidically coupled to a closed-loopliquid operational block.

The pump can be a first pump, and the system can further include atleast one other pump having a corresponding pump inlet fluidicallycoupled to the reservoir and a pump outlet. Each of the pumps can beconfigured to pump the liquid from the reservoir through thecorresponding pump outlet to a different liquid conduit.

The control logic can be configured to iteratively activate anddeactivate each of the plurality of pumps.

The control logic can be configured to iteratively activate anddeactivate each of the plurality of pumps sequentially.

The control logic is configured to iteratively activate and deactivateeach of the plurality of pumps in concurrently or jointly.

A rack-mountable server system can include a manifold module having adistribution manifold and a collection manifold, with each manifoldbeing configured to contain a liquid. A rack can be configured toreceive a plurality of independently operable servers and can include abranch of a heat-transfer system configured to convey the liquid from aninlet to the branch to an outlet from the branch. The inlet can befluidly couplable with the distribution manifold and the outlet can befluidly couplable with the collection manifold. The branch cancorrespond with a first server of the plurality of servers, and eachother server can have a corresponding branch of the heat-transfer systemhaving an inlet fluidly coupled to the distribution manifold and anoutlet fluidly coupled to the collection manifold. The rack-mountableserver system can also include a a fluid conditioning unit. The fluidconditioning unit can include a reservoir configured to receive theliquid via an inlet fluidically couplable to the collection manifold andto hold the liquid. A heat exchange component can be fluidicallycouplable to the distribution manifold. A pump can be coupled to thereservoir with a first liquid conduit, and the pump can be configured topump the liquid from the reservoir to the heat exchange component. Asensor can be configured to observe an operational parameter in thesystem. The system can also include control logic configured tocommunicate a control signal to the pump; receive a signal from thesensor; and iteratively activate and deactivate the pump via the controlsignal until the signal received from the sensor comprises an indicationthat the fluid conditioning unit is filled with a liquid to a specifiedamount.

The control logic can also be configured to iteratively activate anddeactivate the pump via the control signal until the signal receivedfrom the sensor comprises an indication that the manifold module isfilled with the liquid to a specified amount.

The control logic can be configured to iteratively activate anddeactivate the pump via the control signal until the signal receivedfrom the sensor comprises an indication that the branches of theheat-transfer system are filled with the liquid to a specified amount.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedinnovations. Those of ordinary skill in the art will appreciate that theexemplary embodiments disclosed herein can be adapted to variousconfigurations and/or uses without departing from the disclosedprinciples. For example, the principles described above in connectionwith any particular example can be combined with the principlesdescribed in connection with another example described herein. Variousmodifications to those embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof this disclosure. Accordingly, this detailed description shall not beconstrued in a limiting sense, and following a review of thisdisclosure, those of ordinary skill in the art will appreciate the widevariety of filtering and computational techniques can be devised usingthe various concepts described herein.

Similarly, the presently disclosed inventive concepts are not intendedto be limited to the embodiments shown herein, but are to be accordedtheir full scope consistent with the principles underlying disclosedconcepts, wherein reference to an element in the singular, such as byuse of the article “a” or “an” is not intended to mean “one and onlyone” unless specifically so stated, but rather “one or more”. Allstructural and functional equivalents to the elements of the variousembodiments described throughout the disclosure that are known or latercome to be known to those of ordinary skill in the art are intended tobe encompassed by the features described and claimed herein. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure may ultimately explicitly berecited in the claims. No element or concept disclosed herein orhereafter presented shall be construed under the provisions of 35 USC112(f) unless the element or concept is expressly recited using thephrase “means for” or “step for”.

Thus, in view of the many possible embodiments to which the disclosedprinciples can be applied, we reserve the right to claim any and allcombinations of features and acts described herein, including the rightto claim all that comes within the scope and spirit of the foregoingdescription, as well as the combinations recited, literally andequivalently, in the following claims and any claims presented anytimethroughout prosecution of this application or any application claimingbenefit of or priority from this application.

We currently claim:
 1. A system, comprising: an enclosure having aninlet to the enclosure and a wall at least partially defining a boundaryof the enclosure, wherein the enclosure is configured to receive aliquid from the inlet and to contain the received liquid; an aperture inthe wall; a conduit coupled with the aperture, wherein the conduitcomprises a segment extending into the enclosure from the aperture; anda baffle defining a corresponding plurality of apertures, wherein thebaffle is positioned between the inlet and the segment of the conduit,wherein the baffle is oriented such that liquid received from the inletpasses through the plurality of apertures in the baffle before enteringthe segment of conduit.
 2. The system of claim 1, wherein the segment ofconduit extending into the enclosure defines an arcuate segment suchthat an end of the segment of conduit is positioned lower, relative togravity, than a centroid of the aperture in the wall.
 3. The system ofclaim 2, wherein the segment of the conduit extending into the enclosuredefines an end positioned distally from the aperture in the wall,wherein the end defines a second aperture and wherein the secondaperture is oriented transversely relative to the aperture in the wall.4. The system of claim 2, wherein the segment of the conduit extendinginto the enclosure defines an end positioned distally from the aperturein the wall, wherein the end defines a second aperture and wherein thesecond aperture is oriented transversely relative to the baffle.
 5. Thesystem of claim 1, wherein the baffle is a first baffle and thecorresponding plurality of apertures is a first plurality of apertures,wherein the system further comprises a second baffle defining a secondplurality of apertures.
 6. The system of claim 5, wherein each of thefirst plurality of apertures and the second plurality of apertures has acorresponding hydraulic diameter characteristic of the respectiveplurality of apertures, wherein the hydraulic diameter characteristic ofthe first plurality of apertures differs from the hydraulic diametercharacteristic of the second plurality of apertures.
 7. The system ofclaim 6, wherein the baffles are arranged in order of decreasinghydraulic diameter along a direction extending from the inlet to theconduit segment.
 8. The system of claim 5, wherein a hydraulic diametercharacteristic of the first plurality of apertures is substantiallyequal of a hydraulic diameter characteristic of the second plurality ofapertures.
 9. The system of claim 5, wherein the plurality of aperturesof the first baffle is offset from the plurality of apertures of thesecond baffle.
 10. A system comprising: a reservoir defining an inletand an outlet, and configured to hold a liquid received from the inlet;a pump fluidically coupled to the reservoir and configured to pump theliquid from the reservoir to a fluid conditioning unit; a sensorconfigured to observe an operational parameter; and control logicconfigured to: communicate a control signal to the pump; receive asignal from the sensor; and iteratively activate and deactivate the pumpvia the control signal until the signal received from the sensorcomprises an indication that the fluid conditioning unit is filled witha liquid to a specified amount.
 11. The system of claim 10, furthercomprising: a fill tank fluidically coupled to the reservoir; and asecond pump configured to pump liquid from the fill tank to thereservoir; wherein the control logic is configured to communicate asecond control signal to the second pump to activate and deactivate thesecond pump.
 12. The system of claim 10, wherein the sensor comprises atemperature sensor, a pressure sensor, a liquid detection sensor, a flowsensor, or a fluid level sensor.
 13. The system of claim 10, comprisinga plurality of pumps fluidically coupled to the reservoir, each of theplurality of pumps configured to pump the liquid from the reservoir tothe closed-loop liquid system.
 14. The system of claim 13, wherein thecontrol logic is configured to iteratively activate and deactivate eachof the plurality of pumps.
 15. The system of claim 14, wherein thecontrol logic is configured to iteratively activate and deactivate eachof the plurality of pumps sequentially.
 16. The system of claim 14,wherein the control logic is configured to iteratively activate anddeactivate each of the plurality of pumps concurrently.
 17. A controlsystem for a heat-transfer system, the control system comprising: aplurality of sensors, wherein each sensor is configured to observe anoperational parameter indicative of a thermodynamic quantity and to emita signal containing information corresponding to the observedoperational parameter; control logic comprising a processing unit andinstructions stored on a memory that, when executed by the processingunit, cause the control logic to: determine a first thermodynamicquantity associated with each sensor from information contained in asignal from the respective sensor; determine a second thermodynamicquantity associated with each sensor from information contained in asignal received from at least one other sensor in the plurality ofsensors; compare the first thermodynamic quantity with the secondthermodynamic quantity; and responsive to the comparison of the firstthermodynamic quantity with the second thermodynamic quantity, output acontrol signal.
 18. The control system according to claim 17, whereinthe instructions that cause the control logic to output a control signalresponsive to the comparison of the first thermodynamic quantity withthe second thermodynamic quantity comprise instructions to output thecontrol signal responsive to a difference between the firstthermodynamic quantity and the second thermodynamic quantity exceeding athreshold difference, or instructions to output the control signalresponsive to a difference between the first thermodynamic quantity andthe second thermodynamic quantity falling below a threshold difference.19. The control system according to claim 17, wherein the plurality ofsensors comprises a temperature sensor, and wherein the instructionsthat cause the control logic to determine a second thermodynamicquantity comprise instructions that cause the control logic to predict atemperature corresponding to the temperature sensor from informationcontained in a signal received from at least one other sensor in theplurality of sensors.
 20. The control system according to claim 17,wherein the plurality of sensors comprises a pressure sensor, andwherein the instructions that cause the control logic to determine asecond thermodynamic quantity comprise instructions that cause thecontrol logic to predict a pressure corresponding to the pressure sensorfrom information contained in a signal received from at least one othersensor in the plurality of sensors.